FULL-SCALE IN-FLIGHT PRESSURE MEASUREMENTS ON A WNGLET FITTED TO AN AS-W 20

Abstract

In order to gain more insight into the effectiveness of a custom-built winglet on an ASW 20, full-scale inflight pressure measurements were performed. A 96-port scannivalve was used to measure pressures at 78 positions on the surface of a specially built hollow winglet. Data was recorded on a data logger. It was found that a change of lift coefficient from 0.43 to 0.6 caused a very substantial change in the pressure distribution on the inner surface of the winglet. There was also substantial spanwise variation in the pressure near the leading edge of the winglet, leading one to conclude that the twist angle is probably quite far from optimum. In order to evaluate the validity of a three dimensional panel method to this kind of problem, the experimental results were also compared to a CFD (Computational Fluid Dynamics) analysis. Although good agreement was found at one spanwise station, experimental and computational results generally differed substantially, even when wake relaxation was used. It is concluded that satisfactory computational results for this kind of problem can probably only be obtained from a full field method, like an Euler code.